The last paragraph of the treatise De Interpretatione discusses the question of Contraries and Contradictories, and makes out that the greatest breadth of opposition is that between a proposition and its contradictory (Kallias is just--Kallias is not just), not that between, a proposition and what is called its contrary (Kallias is just--Kallias is unjust); therefore, that according to the definition of contrary, the true contrary of a proposition is its contradictory.[53] This paragraph is not connected with that which precedes; moreover, both the reasoning and the conclusion differ from what we read as well in this treatise as in other portions of Aristotle. Accordingly, Ammonius in the Scholia, while informing us that Porphyry had declined to include it in his commentary, intimates also his own belief that it is not genuine, but the work of another hand. At best (Ammonius thinks), if we must consider it as the work of Aristotle, it has been composed by him only as a dialectical exercise, to debate an unsettled question.[54] I think the latter hypothesis not improbable. The paragraph has certainly reference to discussions which we do not know, and it may have been composed when Aristotle had not fully made up his mind on the distinction between Contrary and Contradictory. Considering the difficult problems that he undertook to solve, we may be sure that he must have written down several trains of thought merely preliminary and tentative. Moreover, we know that he had composed a distinct treatise 'De Oppositis,'[55] which is unfortunately lost, but in which he must have included this very topic--the distinction between Contrary and Contradictory. [Footnote 53: Aristot. De Interpr. p. 23, a. 27, seq.] [Footnote 54: Scholia ad Arist. pp. 135-139, Br. [Greek: gumna/sai mo/non boulêthe/ntos tou\s e)ntugcha/nontas pro\s tê\n e)pi/krisin tô=n pithanô=s me\n ou) me/ntoi a)lêthô=s legome/nôn lo/gôn] &c. (p. 135, b. 15; also p. 136, a. 42).] [Footnote 55: Scholia ad Categorias, p. 83, a. 17-19, b. 10, p. 84, a. 29, p. 86, b. 42, p. 88, a. 30. It seems much referred to by Simplikius, who tells us that the Stoics adopted most of its principles (p. 83, a. 21, b. 7).] Whatever may have been the real origin and purpose of this last paragraph, I think it unsuitable as a portion of the treatise De Interpretatione. It nullifies, or at least overclouds, one of the best parts of that treatise, the clear determination of _Anaphasis_ and its consequences.